The goal of this research is to make a chemical measurement system for real-time detection of volatile organic compounds (VOCs) using silicon micromachined components, including ultrasonic flexural-plate-wave (FPW) sensors. This system will be designed for use in personal chemical exposure monitors. It will be small, robust, battery-operated, sensitive enough to detect VOCs at a fraction of the OSHA permissible exposure level and selective enough to identify toxic chemicals in a realistic environment. In this phase, we will design and build a chemical identification chip incorporating an FPW sensor and an on-chip preconcentrator with its associated heater. We will design and test control circuitry and algorithms, and measure system performance upon exposure to two different volatile organic compounds in the presence of water vapor.